A centrifugal pump blade frequency line spectrum flow noise sound source modeling method

Abstract

The embodiment of the present application provides a centrifugal pump blade frequency line spectrum flow noise sound source modeling method in the form of spatial distribution dipole cluster, comprising: three-dimensionally splitting a moving blade of a pump set into independent three-dimensional models, wherein the moving blade comprises a plurality of main blades and a plurality of splitter blades; cutting the flow surface of the moving blade along the chord length direction of the moving blade to form a plurality of segments; performing dipole acoustic equivalent processing on each segment of the plurality of segments of the moving blade to obtain an equivalent sound source; and using the obtained equivalent sound source to establish a pump set-pipeline sound field finite element model and perform simulation calculation on the pump set inlet pipeline flow noise. The calculation precision is higher than that of the current engineering estimation method, and the problem of sound field grid dependence on the three-dimensional geometric modeling of the impeller in the surface sound source method is avoided. Technical support is provided for the performance evaluation of the through-hull system pump set flow noise and the control effect analysis of the system flow noise control scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship machinery noise control, and particularly relates to a centrifugal pump blade frequency line spectrum flow noise sound source modeling method. BACKGROUND

[0002] Underwater noise performance is a key performance affecting the development and application of high-performance ships, and one of the main noise sources of high-performance ships is a centrifugal pump group of a high-flow through-hull system. Periodic pulsating hydrodynamic force generated by high-speed rotation of the pump impeller produces high-magnitude blade frequency line spectrum noise, which has an important influence on the underwater noise of the ship and is the focus of through-hull system noise control.

[0003] In ship engineering practice, there are two measures commonly used to control the flow noise of the through-hull system: one is to develop a low-noise seawater pump to reduce the magnitude of the blade frequency flow noise at the source; and the other is to install a silencer on the pipeline to control the system noise on the transmission path. Whether it is the development of a low-noise seawater pump or the through-hull system pipeline flow noise transmission control scheme based on the silencer, it is necessary to carry out rapid and relatively accurate calculation of the magnitude of the seawater pump blade frequency flow noise, so as to optimize the flow noise performance of various pump group design schemes, provide an effective pump group blade frequency sound source for the analysis of the control effect of the flow noise of the through-hull system, and thus ensure the best control effect on the underwater noise of the through-hull.

[0004] The current calculation method for pump group flow noise is divided into two types:

[0005] (1) Engineering estimation method based on flow rate and head

[0006] This method estimates the fluid power of the pump group using the flow rate and head parameters of the pump group. According to experience, the acoustic energy of the flow noise is estimated by a certain proportion, and then the total level and octave band data of the flow noise in a certain frequency band are given. The blade frequency line spectrum noise energy of the through-hull system flow noise accounts for as high as 50%, and engineering needs to carry out single frequency pipeline sound transmission analysis for the blade frequency. Therefore, this estimation method cannot meet the needs of the analysis and evaluation of the blade frequency flow noise in engineering.

[0007] (2) Blade surface sound source method based on acoustic analogy theory

[0008] The blade surface sound source method needs to accurately divide the pump group internal sound field grid according to the three-dimensional geometry of the impeller, and is seriously dependent on the pump group blade modeling scheme. With the optimization and change of the pump group itself, the flow field grid of the pump group needs to be re-divided, which increases the workload of the pump group acoustic performance evaluation and cannot adapt to the rapid iterative design of various pump group schemes. SUMMARY

[0009] In view of the above problems existing in the prior art, and based on engineering practice, it is known that the blade frequency of a low-noise through-hull pump set is usually lower than 300 Hz, and theoretically, the radiation sound field of a low-frequency (not higher than 315 Hz) hydrodynamic force (surface force) is basically equivalent to that of a concentrated force, the embodiment of the present application provides a centrifugal pump blade frequency line spectrum flow noise sound source modeling method, the moving blades are segmented, an acoustic equivalent space distribution dipole cluster is established, in the case that the pump set internal sound field grid is unchanged, the dipole coordinates are changed to quickly adapt to the three-dimensional modeling of the moving blades of the pump set, the high accuracy advantage of the surface sound source method is retained, and the problem of repeated reconstruction of the pump set internal sound field grid is avoided.

[0010] The embodiment of the present application provides a centrifugal pump blade frequency line spectrum flow noise sound source modeling method, which comprises the following steps:

[0011] The three-dimensional moving blades in the pump set impeller are divided into independent three-dimensional models, wherein the moving blades comprise a plurality of main blades and a plurality of splitter blades;

[0012] The flow surface of the moving blades is divided into a plurality of segments along the chord length direction of the moving blades;

[0013] The dipole acoustic equivalent processing is performed on each segment of the plurality of segments of the moving blades, and an equivalent sound source is obtained.

[0014] The obtained equivalent sound source is used to establish a sound field finite element model of the pump set-pipeline, and the flow noise of the pump set inlet pipeline is simulated and calculated.

[0015] In some embodiments of the present application, the flow surface of the moving blades of the centrifugal pump is divided into a plurality of segments along the chord length direction of the blades, and the water dynamic pressure of the flow surface of each single segment is integrated to calculate the water dynamic vector resultant force of the segment, and the calculation formula is as follows:

[0016] The flow surface of the moving blades of the centrifugal pump is divided into a plurality of segments along the chord length direction of the blades, and the water dynamic pressure of the flow surface of each single segment is integrated to calculate the water dynamic vector resultant force of the segment, and the calculation formula is as follows:

[0017]

[0018] In the formula, p represents the water dynamic pressure of the flow surface of the segment; represents the vector area of the flow surface of the i th segment; represents the water dynamic vector resultant force of the i th segment.

[0019] In some embodiments of the present application, the dipole acoustic equivalent processing is performed on each segment of the plurality of segments of the moving blades to obtain an equivalent sound source, and the method comprises the following steps:

[0020] The three-dimensional high-precision flow field distribution of the impeller is calculated, the fluid pressure of each segment is extracted, the water dynamic vector resultant force is integrated and calculated, and the dipole sound source intensity and direction are determined.

[0021] A dipole is arranged at the center of each segment set to form a plurality of spatially distributed dipole clusters corresponding to the number of segments, as the equivalent sound source of the pump group blade frequency spectrum flow noise.

[0022] In some embodiments of the present application, each segment of the plurality of segments of the moving blade is dipole acoustically equivalent processed to obtain an equivalent sound source, specifically:

[0023] For each single segment, the spatial position of the dipole is positioned at the geometric center of the segment, the intensity of the dipole sound source is determined by the size of the hydrodynamic vector resultant force of the segment, and the orientation of the dipole is positioned by the direction of the hydrodynamic vector resultant force of the segment. In acoustics, a single dipole is used to replace the blade segment, and the equivalent dipole sound source calculation formula is as follows:

[0024]

[0025] In the formula: represents the spatial coordinates of the geometric center of the blade segment; represents a unit source intensity dipole; F l represents the lift component of the hydrodynamic vector resultant force of the segment; F d represents the drag component of the hydrodynamic vector resultant force of the segment; represents the rotation speed vector; represents the distance vector of the dipole coordinates from the origin; represents a harmonic parameter related to the rotation angular frequency.

[0026] In some embodiments of the present application, the obtained equivalent sound source is used to establish a pump group-pipeline acoustic field finite element model to simulate and calculate the pump group inlet pipeline flow noise, including:

[0027] The obtained equivalent sound source is used to establish a pump group-pipeline acoustic field finite element model in combination with a finite element analysis tool to simulate and calculate the sound pressure level of the pump group inlet pipeline flow noise.

[0028] In some embodiments of the present application, the method further comprises:

[0029] The simulation calculation result is compared with the test result, and if the deviation is not greater than a set value, it is determined that the engineering evaluation is satisfied.

[0030] In some embodiments of the present application, the set value is a decibel value not greater than 1.8 dB.

[0031] In some embodiments of the present application, the moving blade specifically includes 6 main blades and 6 splitter blades, and when segmenting, each main blade is divided into 6 segments, each splitter blade is divided into 3 segments, and a total of 54 segments are obtained.

[0032] Compared with the prior art, the centrifugal pump blade frequency spectrum flow noise sound source modeling method provided by the embodiment of the application has the beneficial effects that: by means of the spatial distribution of the dipole cluster, a sound source modeling method for calculating the blade frequency spectrum flow noise of the centrifugal pump is provided, the calculation accuracy is higher than that of the current engineering estimation method, and the problem of the grid dependence on the three-dimensional geometry modeling of the impeller in the surface sound source method is avoided. The application can provide technical support for the performance evaluation of the pump group flow noise of the through-hull system and the control effect analysis of the system flow noise control scheme. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The centrifugal pump moving blade segmentation schematic diagram of the centrifugal pump blade frequency spectrum flow noise sound source modeling method provided by the embodiment of the application;

[0034] Figure 2 The spatial distribution dipole cluster equivalent centrifugal pump blade sound source schematic diagram of the centrifugal pump blade frequency spectrum flow noise sound source modeling method provided by the embodiment of the application. DETAILED DESCRIPTION

[0035] In order for those skilled in the art to better understand the technical solutions of the application, the application will be described in detail below with reference to the drawings and specific embodiments.

[0036] The various aspects and features of the application are described herein with reference to the accompanying drawings.

[0037] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting examples, with reference to the annexed drawings.

[0038] It should also be understood that, while the application has been described above with reference to particular embodiments, many alternatives, modifications, and additions can be made without departing from the scope of the application as defined by the claims.

[0039] The above and other aspects, features, and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0040] Specific embodiments of the application are described herein with reference to the accompanying drawings; however, it is to be understood that the embodiments described are merely exemplary of the application and can be embodied in various forms. Well-known and / or redundant functions and structures are not described in detail to avoid obscuring the application in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and a representative basis for teaching one skilled in the art to variously employ the application in virtually any appropriately detailed structure.

[0041] The specification can use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which can refer to one or more embodiments according to the application.

[0042] The embodiment of the application provides a centrifugal pump blade frequency spectrum flow noise sound source modeling method, as shown in Figure 1 and Figure 2 The method comprises the following steps.

[0043] The three-dimensional moving blade is split into independent three-dimensional models from the pump set impeller, wherein the moving blade comprises a plurality of main blades and a plurality of splitter blades.

[0044] The moving blade passage surface is cut into a plurality of segments along the chord length direction of the moving blade.

[0045] In the embodiment, the moving blade passage surface is cut into a plurality of segments along the chord length direction of the moving blade, which comprises the following steps.

[0046] The moving blade passage surface is cut into a plurality of segments along the chord length direction of the moving blade, and the hydrodynamic pressure of the passage surface is integrated for each single segment to calculate the hydrodynamic vector resultant force of the segment, and the calculation formula is as follows.

[0047]

[0048] In the formula, p represents the hydrodynamic pressure of the passage surface of the segment. represents the vector area of the passage surface of the i th segment. represents the hydrodynamic vector resultant force of the i th segment.

[0049] The dipole acoustic equivalent processing is performed on each segment of the plurality of segments of the moving blade to obtain an equivalent sound source.

[0050] In some embodiments of the application, the dipole acoustic equivalent processing is performed on each segment of the plurality of segments of the moving blade to obtain an equivalent sound source, which comprises the following steps.

[0051] The three-dimensional high-precision flow field distribution of the impeller is calculated, the fluid pressure of each segment is extracted, the hydrodynamic vector resultant force is integrated and calculated, and the intensity and direction of the dipole sound source are determined.

[0052] A dipole is arranged at the center of each segment set to form a plurality of spatially distributed dipole clusters corresponding to the number of segments, as the equivalent sound source of the pump set blade frequency spectrum flow noise.

[0053] Specifically, in the embodiment, the dipole acoustic equivalent processing is performed on each segment of the plurality of segments of the moving blade to obtain an equivalent sound source, and specifically comprises the following steps.

[0054] For each individual segment, the spatial position of the dipole is located by the geometric center of the segment, the intensity of the dipole sound source is determined by the magnitude of the resultant hydrodynamic vector force of the segment, and the orientation of the dipole is determined by the direction of the resultant hydrodynamic vector force of the segment. Acoustically, a single dipole is used to replace the blade segment. The equivalent dipole sound source calculation formula is as follows:

[0055]

[0056] In the formula: Spatial coordinates representing the geometric center of the blade segment; F represents a unit source intensity dipole; l F represents the lift component of the resultant hydrodynamic vector force of the segments; d This represents the drag component of the resultant force of the segmented hydrodynamic vector; Represents the rotational speed vector; This represents the distance vector between the dipole coordinates and the origin. This represents the harmonic parameters related to the rotational angular frequency.

[0057] Using the obtained equivalent sound source, a finite element model of the sound field of the pump set-pipeline is established, and the flow noise of the pump set inlet pipe is simulated and calculated, including:

[0058] Using the obtained equivalent sound source and combined with finite element analysis tools, a finite element model of the sound field of the pump set-pipeline was established, and the sound pressure level of the flow noise in the pump set inlet pipeline was simulated and calculated.

[0059] Furthermore, the method also includes: comparing the simulation calculation results with the experimental test results; if the deviation is not greater than a set value, then the engineering evaluation is deemed satisfactory. As an example, the set value can be a decibel value not greater than 1.8 dB.

[0060] To facilitate understanding of the above technical solutions, the specific implementation of the present invention will be described below using a model of a sea-crossing pump set as an example:

[0061] Step 1: First, disassemble the moving blades of the pump impeller into independent 3D models. The moving blades consist of 6 main blades and 6 branch blades. See Appendix for details. Figure 2 As shown.

[0062] Step Two: Segment the moving blades along the chord length. For example, divide each main blade into 6 segments and each branch blade into 3 segments, for a total of 54 segments. See Appendix for details. Figure 2 As shown.

[0063] Step three: using commercial CFD software, calculate the three-dimensional high-precision flow field distribution of the impeller, extract the fluid pressure of each segment, integrate the hydrodynamic force vector, determine the intensity and direction of the dipole sound source, set a dipole at the center of each segment cluster to form a 54-space distributed dipole cluster as the equivalent sound source of the pump group blade frequency spectrum flow noise, see the attached Figure 2

[0064] Step four: using the sound source, with the help of commercial acoustic finite element software, establish a finite element model of the pump group-pipeline sound field, simulate the sound pressure level of the pump group inlet pipeline flow noise, the deviation is not more than 1.8dB, which meets the accuracy requirements of engineering evaluation, see the table below.

[0065] Serial number Working condition description The present application Test value Deviation 1 980r / min, flow 300t / h, blade frequency 98Hz 159.1dB 158.9dB 0.2dB 2 686r / min, flow 210t / h, blade frequency 68.6Hz 162.5dB 160.7dB 1.8dB

[0066] Through the above technical scheme, the above embodiment of the present application provides a centrifugal pump blade frequency spectrum flow noise sound source modeling method by means of spatial distribution of dipole cluster, which has higher calculation accuracy than the current engineering estimation method, and avoids the problem of sound field grid dependence on three-dimensional geometric modeling of the impeller in the surface sound source method. The present application can provide technical support for the performance evaluation of the through-hull system pump group flow noise and the control effect analysis of the system flow noise control scheme.

[0067] The above embodiments are only exemplary embodiments of the present application and are not used to limit the present application, and the protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements should also be considered to fall within the protection scope of the present application.​

Claims

1. A method of modeling a centrifugal pump blade passage line spectrum flow noise source, the method comprising: The method comprises the following steps: three-dimensionally splitting the moving blade of the pump set impeller into independent three-dimensional models, wherein the moving blade comprises a plurality of main blades and a plurality of splitter blades; cutting the moving blade passage surface along the chord length direction of the moving blade to form a plurality of segments, comprising: calculating the three-dimensional high-precision flow field distribution of the impeller, extracting the fluid pressure of each segment, integrating the hydrodynamic force vector resultant force to determine the intensity and direction of the dipole sound source; setting a dipole at the center of each segment set to form a plurality of spatially distributed dipole clusters corresponding to the number of segments, as the equivalent sound source of the pump set blade frequency spectrum flow noise; performing dipole acoustic equivalent processing on each segment of the plurality of segments of the moving blade to obtain the equivalent sound source, specifically: for each single segment, positioning the spatial position of the dipole at the geometric center of the segment, determining the intensity of the dipole sound source according to the size of the hydrodynamic force vector resultant force of the segment, and positioning the orientation of the dipole according to the direction of the hydrodynamic force vector resultant force of the segment, and in acoustics, replacing the blade segment with a single dipole, and the equivalent dipole sound source calculation formula is as follows: wherein: represents the spatial coordinates of the geometric center of the blade segment; represents a unit source strength dipole; F l represents the lift component of the segmented hydrodynamic force vector sum; F d represents the drag component of the segmented hydrodynamic force vector sum; represents the rotational speed vector; represents the distance vector of the dipole coordinates from the origin; represents the harmonic parameter related to the rotational angular frequency; using the obtained equivalent sound source, establishing a pump set-pipeline sound field finite element model, and simulating and calculating the pump set inlet pipeline flow noise.

2. The method of claim 1, wherein, The method further comprises: cutting the moving blade passage surface along the chord length direction of the moving blade to form a plurality of segments, comprising: where: p represents the hydrodynamic pressure of the segmented flow surface; represents the vector area of the i-th segmented flow surface; represents the hydrodynamic vector resultant force of the i-th segment.

3. The method of claim 2, wherein, cutting the moving blade passage surface of the centrifugal pump moving blade into a plurality of segments along the chord length direction of the blade, for each single segment, integrating the hydrodynamic pressure of the passage surface to calculate the hydrodynamic force vector resultant force of the segment, and the calculation formula is as follows: The method further comprises:

4. The method of claim 3, wherein, using the obtained equivalent sound source, combining with the finite element analysis tool, establishing a pump set-pipeline sound field finite element model, and simulating and calculating the pump set inlet pipeline flow noise sound pressure level. The method further comprises: comparing the simulation calculation result with the test result, if the deviation is not greater than the set value, it is determined that the engineering evaluation is satisfied.

5. The centrifugal pump blade frequency spectrum flow noise sound source modeling method according to claim 4, wherein the set value is a decibel value not greater than 1.8 dB.

6. The centrifugal pump blade frequency spectrum flow noise sound source modeling method according to claim 5, wherein the moving blade specifically comprises 6 main blades and 6 splitter blades, and when segmenting, each main blade is divided into 6 segments, and each splitter blade is divided into 3 segments, a total of 54 segments.

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